1. Field of the Invention
The present invention relates to a display/input device.
2. Description of the Related Art
In recent years, a small electronic device is often provided with a touch panel as an input device for inputting information or for operating a graphical user interface (hereinafter, a GUI). By using a touch panel, it becomes unnecessary to separately provide an input section such as a keyboard, and thus an electronic device can be miniaturized. Furthermore, a touch panel is also a display device on which an image, a GUI or the like is displayed. Thus, by using a touch panel, an intuitive operating system for directly touching and operating an image, a GUI or the like displayed on the touch panel can be realized. Having these features, a touch panel is mounted on various electronic devices, such as a mobile information terminal, a mobile phone, a car navigation system, a lap-top personal computer, or an information appliance.
As described above, a touch panel has a function of an input device and a function of a display device. The function of a display device is realized by using a display panel, such as a liquid crystal display panel (hereinafter, an LCD panel) or an organic electroluminescent display panel (hereinafter, an OELD panel), for example. On the other hand, the function of an input device is realized by providing on a display panel a capacitive sensor or an optical sensor for optically scanning an operating tool that is brought into proximity of or made to contact the surface of the display panel. In many cases, a sensor area where sensing by the capacitive sensor or the optical sensor is possible is set in a pixel area (displayable area) on the display panel. Furthermore, Japanese Patent No. 4161814 discloses a technology for expanding the sensor area to the frame portion of a display panel and realizing a convenient operating system by using the expanded sensor area.